Fluid pressure equalizing arrangement



May 25, 1937. J. H. DORAN FLUID PRESSURE EQUALIZING ARRANGEMENT Filed July 27, 1934 as J T n mmflw eH a... v L mhww m. m

Patented May 25, 1937 UNITED STATES FLUID PRESSURE EQUALIZING ARRANGEMENT John H. Doran, Scotia, N. Y., assig'nor to General Electric Company, a corporation of New York Application July 27, 1984, Serial No. 737,236

1 Claim. (01. 103-224) The invention relates to fluid pressure equalizing arrangements and devices. Such devices are provided, for example, in connection with reciprocating pumps toequalize, reduce or mini- 5 mize fluctuations or pulsations in pressure of the fluid discharged by reciprocating pumps. The pulsations of the fluid discharged by reciprocating pumps have an intensity depending on the number of cylinders of the pump. For instance,

10 with a five-cylinder pump the variation in flow is of the order of about 8% of the normal or average flow. The fluctuations tend to increase with decreasing number of cylinders, reaching a maximum in case a single cylinder is provided 15 for forcing fluid through a conduit. These fluctuations or pulsations are undesirable. They often lead toconsiderable vibration of the conduits which may cause breaking thereof.

The object of my invention is to provide an 20 improved construction and arrangement of pressure equalizing arrangements and devices whereby fluctuations or pulsations in pressure of a fluid forced through a conduit are substantially reduced, damped or equalized.

5 For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claim appended thereto in connection with the accompanying drawing. 30 In the drawing, Fig. 1 is a sectional view showing a pressure equalizing arrangement embodying my invention, and Figs. 2 and 3 are similar views showing modifications of my invention.

The arrangement (Fig. 1) comprises a recipro- 35 cating pumping means or pump I having a cylinder II and a piston I2 movably arranged within the cylinder. The piston is connected to a stem I3 which is 'reciprocated by any suitable means, not shown. The cylinder has an inlet or 40 suction conduit I4 with an inlet or suction valve l5 and an outlet or discharge conduit I6 with an outlet or discharge valve Il. The outlet i6 is connected to a'conduit 18. This is a known type of reciprocating pump. During operation, up- 45 ward movement of the piston I2 creates a vacuum in the cylinder whereby fluid such as water flows through the inlet conduit l4 into the cylinder, the valve l5 being open during upward movement whereas the valve I1 is closed. As the piston I2 50 is moved downward, the inlet valve l5 closes and discharge valve opens whereby the fluid is forced through the outlet l5 into the conduit l8. In order to reduce pulsations in pressure of the fluid discharged from the reciprocating 55 pump, I provide, in accordance with my invention, means for equalizing the pressure fluctuations. This means comprises a device 20 provided in close proximity to the pump I0 and connected to the conduit l8. More specifically, the device 20 includesa cylinder or container 2| cov- 5 ered with heat insulation or lagging 22. The lower or bottom portion of the cylinder communicates with the conduit I8 through a connecting pipe or member 23.

An electric heating element 24 is disposed in 10 the upper portion of the cylinder. The heating device 24 in the arrangement of Fig. 1 comprises a heating coil 25 embedded in a cylindrical body 26 of a material with high heat conductivity such as steel. The body 26 is rigidly secured to the cylinder 2| by welds 21. The heating coil 25 is connected to a source 28 of electric energy. The electric circuit also includes an operating switch 29 and a rheostat 30 having a. movable lever 3| and stops 32 and 33. The lever 3| is connected to a temperature responsive device comprising a bellows 34 and a coil 35 connected to the bellows and disposed in the interior of the cylindrical body 26. .The coil 35 is sealed and filled with a medium such as air which expands as the temperature of the body 26 increases. The upper end of the bellows is pivoted to the lever 3|, which lever is normally biased downward towards the stop 32 by a compression spring 36. With this arrangement the current flowing through the heating resistance 25 is controlled in; response to temperature changes. At low temperatures the resistance of the rheostat 30 is entirely out out,'as shown in Fig. 1, so that a maximum current flows. through the heating resistance 25. An increasing temperature beyond a certain value causes the fluid contained in the coil 35 to expand, effecting expansion of the bellows 34 against the biasing force of the spring 36, resulting in counter-clockwise turning move- 40 ment of the lever 3| and the insertion of some of the resistance of the rheostat 30 into the circuit. The operating switch 29 according to my invention is connected to a pressure responsive device 31 which comprises a casing having two halves separated by a diaphragm 38, which latter is connected to the switch 29 by a link 39 and biased in downward direction by a spring 40. The lower casing half is connected to the conduit l8 adjacent the outlet conduit l6 of the pump by means of a pipe 4|. As soon as the pump I0 is started, the pressure in the pipe 4| and the lower casing half increases, efiecting upward movement of the diaphragm 38 and closing of the switch 29. The switch 29 remains closed as long as the pump In is operated and the switch 29 is automatically opened when the pump Ill is put out of operation. A part of the fluid discharged by the pump is forced through the connecting pipe 23 into the cylinder II. The fluid in the cylinder 2| is heated whereby a cushion of vapor is formed in the upper portion of the cylinder 2|. This vapor cushion damps the pressure fluctuations of the fluid discharged by the pump, that is, as long as the pressure near the connection between the pipe 23 and the conduit l8 increases, fluid is forced into the cylinder 2|, causing compression of the vapor cushion in the upper portion of the cylinder and as thereafter the pressure in the conduit l8 near its connection with the connecting pipe 23 decreases, fluid is forced out of the cylinder 2| by the action of the vapor cushion. When the temperature in the upper portion of the cylinder increases, causing a corresponding increase of the temperature within the coil 35 of the temperature responsive device, the current flowing through the heating resistance 25 is automatically decreased by the insertion of resistance into the circuit of the heating resistance 25. When the temperature increases beyond a certain value, the lever 3| oi the rheostat 30 is forced upward towards the stop 33, in which position the circuit is interrupted. At the end of the operation the electric circuit is automatically interrupted by the action of the pressure responsive device 31 as described above.

The modification shown in Fig. 2 comprises a heat insulated cylinder 42, corresponding to the cylinder 2| of Fig. 1. The arrangement also includes an electric circuit connected to a source 44 corresponding to the source 28 of Fig. l and an operating switch 43 connected to a pressure responsive device 43a. corresponding to the device 31 of Fig. 1. The heating device comprises a coil 45 made of steel or like material with high heat conductivity. The coil 45 is disposed in the upper portion of the cylinder 42 and fastened thereto by a weld 46. A heating resistance 41 is disposed within the steel coil 45 and has its end connected to the source 44 through the intermediary of a contact making member 48. The member 48 forms a part of a relay 49 which has a coil 50 connected to the source 44 through the intermediary of another relay 5|. The latter has a coil 52 connected to the ends of a thermo element 53. The thermo element is disposed within the upper portion of the cylinder'and includes a cylindrical tube 54 fastened to the cylinder 42 by a weld 55. The arrangement is shown in operating condition with the switch 43 and the contact making member in closed position. When the temperature in the upper portion of the cylinder increases it causes a. corresponding increase of current flowing through the coil 52 connected to the thermo element and as the current flowing through coil 52 reaches a certain value the relay 5| is forced open, thereby interrupting the circuit for the coil 50 or the relay 49. The latter thereby effects opening of the circuit for the heating resistance 41. Also here the switch 43 represents a means for closing the heating circuit in response to the discharge pressure of a pump, and the thermo element together with the relays 49 and 5| represent means for automatically interrupting the circuit of the heating resistance 41 as the temperature in the upper portion of the cylinder rises beyond a certain value.

The arrangement shown in Fig. 3 comprises a heat-insulated cylinder 60 corresponding to the cylinder 2| of Fig. 1. I'he heating device in this arrangement includes a cup-shaped body Si inserted in an opening of the cylinder and secured thereto by a weld 62. A heating elementcomprising a heating resistance 53 with two terminals 64 and 65 is disposed in the interior of the cup shaped body 6|. In order to improve the heat transfer from the heating resistance to the body 6|, which latter is made of a material with high heat conductivity, I fill said body with a medium 66 of high heat conductivity, preferably a metal of low melting point such as mercury. The upper end of the space defined within the cupshaped body 6| is connected to the atmosphere through a breather pipe 61. The arrangement also includes a thermo element 58 corresponding to the thermo element 53 of Fig. 2.

With my invention I have accomplished an improved construction and arrangement for fluid pressure equalizing arrangements and devices. The devices in accordance with my invention include heating means which are automatically connected as a pump is put into operation and disconnected as the pump is put out of operation. The heating devices in a preferred embodiment include a heating resistance and means for automatically regulating the flow of current therethrough in response to temperature conditions.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

The combination of a reciprocating pump, a conduit connected to the outlet of the pump for conducting liquid to an elastic fluid generator, a device connected to the conduit in close proximity to the pump for equalizing fluctuations in pressure of the liquid discharged by the pump into the conduit, said device comprising a closed cylinder communicating with the conduit, a helically wound electrical heating resistance disposed within an upper portion of the cylinder and partly immersed in liquid during normal op-- erating conditions, an electric circuit for the resistance, said circuit including a switch and a relay having a contact-making member in series with the switch, means including a pressure-responsive device connected to the outlet of the pump for automatically actuating the switch, and other means for automatically opening said relay to disconnect the resistance as the temperature in the cylinder reaches a predetermined high value, said other means including an electric circuit with another relay for energizing the first named relay and a thermo element centrally disposed within the spiral and normally partly immersed in liquid to energize the other relay to eifect opening of the other relay and deenergization of the first mentioned relay in response to a predetermined high temperature in the cylinder.

JOHN H. DORAN. 

